{"title":"In Situ Probing and Phosphate-Assisted Recovery of Proton Transfer to Eliminate H<sub>2</sub>O<sub>2</sub> Formation in the Oxygen Reduction Reaction.","authors":"Xiang Li, Chuanqi Cheng, Qingqing Ruan, Ying Gao, Lingjun Kong, Yanmei Shi, Bin Zhang","doi":"10.1021/jacs.5c07815","DOIUrl":null,"url":null,"abstract":"<p><p>Single-atom Fe-N-C is a promising candidate for the oxygen reduction reaction (ORR) at the cathode of proton-exchange membrane fuel cells (PEMFCs). However, under strongly acidic conditions, Fe-N-C suffers from severe oxidation from Fenton reactions caused by trace amounts of dissolved Fe and a 2-electron (2e) ORR product of H<sub>2</sub>O<sub>2</sub>. Herein, we demonstrate a facile and general strategy to nearly eliminate the 2e path of the ORR by introducing phosphates. We discover that bubbling O<sub>2</sub> into water introduces an inherent problem in breaking the hydrogen-bond network and thus hindering proton transfer, resulting in a decreased 4e ORR selectivity. Introducing phosphates is found to recover the hydrogen-bond network to eliminate the 2e path. This strategy works well for Fe-N-C, commercial Pt/C, and even carbon catalysts with a dominant 2e selectivity, resulting in negligible H<sub>2</sub>O<sub>2</sub> production and better stability in both the rotating ring-disk electrode system and flow cell. Our work provides deep insight into the ORR mechanism and a useful strategy to lower the cost and lengthen the lifetime of PEMFCs by using nonnoble metal electrocatalysts as cathodes.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":" ","pages":""},"PeriodicalIF":14.4000,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the American Chemical Society","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/jacs.5c07815","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Single-atom Fe-N-C is a promising candidate for the oxygen reduction reaction (ORR) at the cathode of proton-exchange membrane fuel cells (PEMFCs). However, under strongly acidic conditions, Fe-N-C suffers from severe oxidation from Fenton reactions caused by trace amounts of dissolved Fe and a 2-electron (2e) ORR product of H2O2. Herein, we demonstrate a facile and general strategy to nearly eliminate the 2e path of the ORR by introducing phosphates. We discover that bubbling O2 into water introduces an inherent problem in breaking the hydrogen-bond network and thus hindering proton transfer, resulting in a decreased 4e ORR selectivity. Introducing phosphates is found to recover the hydrogen-bond network to eliminate the 2e path. This strategy works well for Fe-N-C, commercial Pt/C, and even carbon catalysts with a dominant 2e selectivity, resulting in negligible H2O2 production and better stability in both the rotating ring-disk electrode system and flow cell. Our work provides deep insight into the ORR mechanism and a useful strategy to lower the cost and lengthen the lifetime of PEMFCs by using nonnoble metal electrocatalysts as cathodes.
期刊介绍:
The flagship journal of the American Chemical Society, known as the Journal of the American Chemical Society (JACS), has been a prestigious publication since its establishment in 1879. It holds a preeminent position in the field of chemistry and related interdisciplinary sciences. JACS is committed to disseminating cutting-edge research papers, covering a wide range of topics, and encompasses approximately 19,000 pages of Articles, Communications, and Perspectives annually. With a weekly publication frequency, JACS plays a vital role in advancing the field of chemistry by providing essential research.